In one widely practiced method of lining pipes, here disclosed by way of example only, certain aspects of which are disclosed in Wood U.S. Pat. No. 4,064,211 of Dec. 20, 1977 entitled "Lining of Passageways", flexible lining tubes are utilized. These tubes comprise a resin-absorbent material which serves to soak up a curable synthetic resin. The resin-impregnated tube, initially flexible, is inserted into the pipe and then forced radially outwardly into engagement with the internal pipe surface by internally pressurizing the flexible tube by means of pneumatic or hydraulic pressure, with or without providing a vacuum in the initial space between the tube and the pipe. After that internal pressurization, the resin with which the tube is impregnated cures, thus producing a rigid lining within the pipe which ideally closely conforms to the entire inner surface of the pipe. These insertion procedures are carried out at relatively widely spaced intervals along the length of the pipe, and in general the lining procedures of the prior art have involved producing a lining continuously from one manhole opening to the next. The longer the lining the more costly is the procedure.
There are instances where the overall condition of a pipe does not warrant complete relining, but a small section of the pipe has failed or been damaged, calling for, in effect, a patch-type of repair rather than an overall reconstruction. Since, as has been pointed out, in most relining processes the lining when positioned must be firmly pressed outwardly into engagement with the inner surface of the pipe, an action which existing technology can readily perform when lining from one manhole to the next, problems have arisen in effecting that outward pressure when only short lining lengths at locations remote from the manhole access openings are involved.
In addition, when a damaged pipe is to be repaired it is quite frequently the case that the inside of that pipe contains foreign material, such as accumulated water and solid fragments, which, if permitted to remain between the new lining and the old pipe, will seriously adversely affect the efficacy of the lining repair. It therefore is important that such foreign material be eliminated from the area where the lining is to be applied, and accomplishing that elimination is often difficult, particular if the pipe is not straight.
Since patch-type repairs of the type under discussion are by no means uniform from installation to installation it is essential that any truly feasible short length repair method and apparatus be readily adaptable to providing repairs of different lengths so as to be adaptable to different situations as they arise.
A truly effective patch-type repair system must not only produce a proper, effective and reliable lining where that lining is needed, but must also do so in a fashion that can be readily performed and controlled remotely and do so at a minimal cost.